Introduction
Severe hypertension during pregnancy is a risk factor for cardiovascular problems, and hypertension persists even after pregnancy. Normal blood pressure in pregnancy should be less than 120 mmHg (millimeter of mercury) systolic and 80 mmHg diastolic. Severe hypertension has a systolic blood pressure above 160 mmHg and diastolic blood pressure above 110 mmHg. Hospital assessment is always essential for severe hypertension that occurs in pregnancy.
What Is Hypertension?
Hypertension is also known as high blood pressure (BP). Blood pressure is measured as two values - systolic blood pressure and diastolic blood pressure. The upper value, systolic blood pressure, measures the pressure inserted in the arteries whenever the heart beats. The lower value, diastolic blood pressure, measures the arterial pressure when the heart rests between beats. A normal blood pressure range is less than 120/80 mmHg. If the blood pressure is consistently 140/90 mmHg or higher, it indicates a high blood pressure condition.
What Is Severe Hypertension in Pregnancy?
Severe hypertension in pregnancy occurs when the systolic blood pressure is 160 mmHg or above and the diastolic BP is 110 mmHg or above.
How Is Severe Hypertension Caused in Pregnancy?
Hypertension affecting pregnant women is due to pregnancy-induced hypertension disorders like preeclampsia or any preexisting chronic hypertension.
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Chronic Hypertension - Severe hypertension before 20 weeks of gestation is rare but usually occurs due to chronic hypertension. The blood pressure range may be greater than 140/90 mmHg in chronic hypertension. If routine blood pressure checks aren't done before pregnancy, chronic hypertension can be diagnosed for the first time during pregnancy. Chronic hypertension also persists after the birth of the child.
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Preeclampsia - Preeclampsia is a high blood pressure disorder during pregnancy and is the most common cause of severe hypertension after 20 weeks of gestation. Preeclampsia during pregnancy can cause fetal growth restriction, preterm birth (delivery before the due date), organ damage, and an increased risk of cardiovascular disease for the mother.
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Preeclampsia Super Imposed on Chronic Hypertension - Women diagnosed with chronic hypertension tend to develop increased blood pressure (preeclampsia), blood in their urine, and other health complications during pregnancy. Both preeclampsia and chronic hypertension are risk factors for cerebrovascular disease, cardiovascular disease, and chronic kidney disease later in life with endothelial dysfunction, chronic inflammatory changes, and angiogenic imbalance.
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Secondary Causes of Hypertension - Secondary causes of hypertension can include conditions like pheochromocytoma, renal artery stenosis due to fibromuscular dysplasia, and primary hyperaldosteronism. Pheochromocytoma is a benign tumor that develops in the adrenal gland. This tumor releases hormones that can cause an increase in blood pressure. Renal artery stenosis due to fibromuscular dysplasia is a condition that narrows and enlarges arteries in the body. This, in turn, causes increased blood pressure. Primary hyperaldosteronism is an endocrine problem where adrenal glands produce increased levels of aldosterone hormone. This manifests in high blood pressure levels.
An increased systolic and diastolic blood pressure, a longer duration of antihypertensive treatment during pregnancy, and preeclampsia are all risk factors for hypertension to retain after pregnancy.
How Is High Blood Pressure Detected in Pregnancy?
High blood pressure is systolic BP above 140 mmHg and diastolic blood pressure above 90 mmHg. Two measurements must be taken at least four to six hours apart. A high blood pressure condition is confirmed if the two measurements show the same high range. In chronic hypertension, the blood pressure range may be greater than 140/90 mmHg before 20 weeks of gestation. After 20 weeks of pregnancy, if the blood pressure is higher than 140/90 mmHg without any presence of organ damage, it is considered gestational hypertension. It also persists after the birth of the child.
What Is the Acute Management of Severe Hypertension in Pregnancy?
Women with chronic hypertension before pregnancy should be checked for organ damage or evidence of any secondary cause of hypertension, like pheochromocytoma, renal artery stenosis due to fibromuscular dysplasia, and primary hyperaldosteronism.
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Management of secondary causes of hypertensive conditions like renal artery stenosis and pheochromocytoma can be treated before and during pregnancy. Treating these conditions can result in the cure of hypertension. Surgery is the recommended treatment option for pheochromocytoma, and revascularization is the treatment procedure for renal artery stenosis. The pheochromocytoma surgery is usually done after initiating 10 to 14 days of alpha blockage. Renal artery vascularization and surgical removal of pheochromocytoma can be done in all trimesters of pregnancy.
Management of Chronic Hypertension and Preeclampsia - Women with chronic hypertension should also be counseled about the risks of preeclampsia during pregnancy and possible fetal outcomes. The standard treatment option for acute hypertensive pregnancy conditions like preeclampsia is delivery.
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In chronic hypertension and preeclampsia, antihypertensive drugs are started to reduce the blood pressure levels below 160/110 mmHg and to reach the range of 110 - 135 / 70-85 mmHg for the rest of the pregnancy. With the beginning of oral medications, blood pressure can be controlled within days and sometimes within hours.
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Some commonly used oral antihypertensive medications given in pregnancy include Methyldopa, Amlodipine, modified-release Nifedipine, Labetalol, Doxazosin, and Prazosin.
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Modified-release Nifedipine, Methyldopa, and Labetalol are considered safe and some of the most commonly used drugs during pregnancy. No adverse effects have been reported with these medications.
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Medications given through the intravenous route include Labetalol and Hydralazine. Intravenous Labetalol is used for rapid and precise control. Intravenous Hydralazine is given when Labetalol is contraindicated or ineffective or to avoid rapid blood pressure changes and hypotension (BP less than 110/70 mmHg). They are also given when a delivery is expected within the next 48 hours and urgent control of BP is essential.
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Enalapril is the oral medication given in the postpartum period. It is considered safe for the lactation period.
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Angiotensin receptor antagonists and angiotensin-converting enzyme inhibitors are contraindicated during pregnancy as they cause fetus toxicity in the second and third trimesters.
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Additional treatment methods like Magnesium sulfate are given to women with preeclampsia and severe hypertension to reduce the risk of pulmonary edema. It also includes fluid restriction with a careful fluid balance. Intravenous Magnesium sulfate decreases the risk of the start of seizures in pregnant women with preeclampsia (eclampsia) and the death of the mother. This medication does not cause any harm to the baby or the mother. Magnesium sulfate is administered during the delivery or 24 hours after delivery.
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A postpartum rise in blood pressure can occur for both normotensive (normal blood pressure range) and hypertensive women during the third to sixth day after delivery.
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Therefore, preeclampsia and blood pressure should be monitored even in the first-week post-delivery.
Conclusion
Severe hypertension during pregnancy is due to preexisting chronic hypertension and preeclampsia. Severe hypertension can be controlled by identifying and detecting the underlying risk factors and conditions causing hypertension with adequate medical and surgical management without causing significant harm to the baby or the mother.
